The ability to disperse metal ions in polymer matrices, particularly those from which foams are produced (see our U.S. Patent Applications Ser. No. 008,276, filed Jan. 22, 1993 and now abandoned, entitled "Process for the Preparation of Blends and Their Use in Small Cell Foams" and Ser. No. 08/148,440, filed Nov. 8, 1993and now U.S. Pat. No. 5,386,617, entitled "Small Cell Foams and Blends and a Process for Their Preparation") is often fraught with difficulty. Dispersions of metals in polymer matrices have typically been formed using salts, such as metal oleate salts, combined with specific combinations of monomers, but there are problems with this approach. In order to maximize the solubility of the salt, modifications of the polymer matrix are required that change the melt rheology of the matrix and affect its foaming characteristics. In addition, the presence of certain metal oleates, such as copper oleate, in the monomer often inhibit polymerization so that only low molecular weight viscous liquids are obtained. This approach obviously introduces significant variables that must be controlled in order to obtain the desired product. As a result, the complexity of the problem and any potential solutions are vastly increased. Therefore, new methods of dispersing metals in water-immiscible phases in general and in polymer matrices in particular would be most useful.
The formation of a gel in a two phase system (aqueous/organic) has use in an oil/water emulsion system for use as a surfactant. Some known problems arise with regard to holding large quantities of the organic phase within the continuous aqueous phase. As a result, the ability to use a gel for this purpose would be useful.
In recent years, polymers referred to as dense star polymers or dendrimers or as STARBURST.TM. (a trademark of Dendritech Inc.) polymers have been developed. Dense star polymers or dendrimers exhibit molecular architecture characterized by regular dendritic branching with radial symmetry. These radially symmetrical molecules are referred to as possessing "starburst topology". These polymers are made in a manner which can provide concentric dendritic tiers around an initiator core. The starburst topology is achieved by the ordered assembly of repeating units, usually organic groups, in concentric, dendritic tiers around an initiator core; this is accomplished by introducing multiplicity and self-replication (within each tier) in a geometrically progressive fashion through a number of molecular generations. The resulting highly functionalized molecules have been termed "dendrimers" in deference to their branched (tree-like) structure as well as their oligomeric nature. Thus, the terms "dense star oligomer" and "dense star dendrimer" are encompassed within the term "dense star polymer". Also topological polymers, with size and shape controlled domains, are dense star dendrimers that are covalently bridged through their reactive terminal groups, which are referred to as "dense star bridged dendrimers." The term "dense star bridged dendrimer" is also encompassed within the term "dense star polymer" and "dense star polymer".
These dense star polymers have been previously described as a solvent soluble, radially symmetrical dense star polymer wherein the dense star polymer has at least one core branch emanating from a core, said branch having at least one terminal group provided that (1) the ratio of terminal groups to the core branches is two or greater, (2) the density of terminal groups per unit volume in the polymer is at least 1.5 times that of an extended conventional star polymer having similar core and monomeric moieties and a comparable molecular weight and number of core branches, each of such branches of the extended conventional star polymer bearing only one terminal group, and (3) the dense star polymer has a molecular volume that is no more than about 60 to 80 percent of the molecular volume of said extended conventional star polymer as determined by dimensional studies using scaled Corey-Pauling molecular models, and has regular dendritic branching. (See, for example, the descriptions of dense star polymers in U.S. Pat. Nos. 4,507,466; 4,558,120; 4,568,737; 4,587,329; and 4,694,064; and European Patent Application Publication No. 0 271 180, the disclosures of which are hereby incorporated by reference.) It has been previously found that the size, shape and properties of these dense star polymers can be molecularly tailored to meet specialized end uses (e.g., European Patent Application Publication No. 0 271 180, the disclosure of which is hereby incorporated by reference). Among such specialized end uses, European Patent Application Publication No. 0 271 180, the disclosure of which is hereby incorporated by reference, teaches the use of dense star polymers as carriers for agricultural, pharmaceutical or other materials including metal ions, such as alkali and alkaline-earth metals and radionuclides generated from actinides or lanthanides or other similar transition metals. Such dense star polymer conjugates are particularly useful in delivering carried materials in biological systems. However, nowhere is the use of such structured dense star dendrimers as absorbents, gels and carriers of metal ions taught or suggested.